Deep Eutectic Solvents for Carbon Dioxide Capture

Deep eutectic solvents (DESs) have emerged as a versatile class of designer liquids formed by the complexation of a hydrogen bond donor and a hydrogen bond acceptor. By depressing the melting point compared with the individual constituents, DESs combine the tunability and low volatility of ionic liquids with reduced cost and improved biodegradability. Their remarkable capacity to solvate carbon dioxide arises from a combination of physical absorption in the fluid matrix and specific chemical interactions via hydrogen bonding and van der Waals forces. Tailoring the nature and ratio of the component species allows optimisation of viscosity, density and gas affinity, which in turn governs mass transfer rates and separation performance. Global research efforts have focused on identifying natural and hydrophobic DES combinations that deliver high CO₂ loading, low corrosivity and facile solvent regeneration. Practical applications span post-combustion flue-gas treatment, pre-combustion processes in syngas streams and biogas upgrading. Ongoing challenges include high viscosity under capture conditions, energy requirements for desorption and scale-up of promising solvent systems. Nevertheless, the modular design principles of DESs and their inherent sustainability credentials position them as a frontier technology in the quest for effective carbon management.

Research from Nature Portfolio

Recent studies have applied molecular dynamics simulations to probe the structure and dynamics of a DES composed of choline chloride and phenyl propionic acid. Temperature-dependent self-diffusion coefficients, viscosities and hydrogen bond networks were characterised over a wide range of conditions. Simulated densities and interaction energies showed strong agreement with experimental data, reinforcing the reliability of computational models in screening DES performance. These insights into non-bonding forces and spatial distribution functions provide a rational basis for selecting component pairs and tuning molar ratios to optimise CO₂ solubility and transport properties in next-generation capture solvents.

Deep Eutectic Solvents for Carbon Dioxide Capture publication trend

The graph below shows the total number of articles in deep eutectic solvents for carbon dioxide capture across all publications each year (not limited to Nature Index journals).

Technical terms

Deep Eutectic Solvent (DES): A eutectic mixture of hydrogen bond donor and acceptor components that forms a liquid with a melting point lower than those of its individual constituents.

Hydrogen Bond Donor (HBD): A component in a DES that provides hydrogen atoms capable of forming hydrogen bonds.

Hydrogen Bond Acceptor (HBA): A component in a DES that accepts hydrogen bonds, stabilising the eutectic structure.

Henry’s Law Constant: A measure of the solubility of a gas in a liquid under equilibrium at a given temperature.

References

1. A detailed study of cholinium chloride and levulinic acid deep eutectic solvent system for CO 2 capture via experimental and molecular simulation approaches. Physical Chemistry Chemical Physics (2015).
2. Screening Deep Eutectic Solvents for CO2 Capture With COSMO-RS. Frontiers in Chemistry (2020).
3. Insights into the interactions and dynamics of a DES formed by phenyl propionic acid and choline chloride. Scientific Reports (2021).
4. Deep Eutectic Solvents: Properties and Applications in CO2 Separation. Molecules (2023).
5. Development of Natural Hydrophobic Deep Eutectic Solvents for Precombustion CO2 Capture. ACS Sustainable Chemistry & Engineering (2022).